Talar dome with angled holes

ABSTRACT

A talar implant includes a post projecting from a superior surface of the plate and includes at least one threaded hole. A talar dome having an inferior surface is configured to face the plate and an opening in the inferior surface is shaped to receive the post. The talar dome includes at least one through hole having a threaded surface and a groove. The groove has a larger outer diameter than the threaded surface. At least one fastener is configured to engage the threaded hole of the post and the threaded surface of the through hole. The at least one fastener has a groove that is aligned with the groove of the through hole when the fastener is inserted in the talar dome and the post. At least one clip is configured to engage the groove of the through hole of the talar dome and the groove of the fastener.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.17/168,235, filed Feb. 5, 2021, which is a continuation of U.S. patentapplication Ser. No. 16/297,940, filed Mar. 11, 2019 (now U.S. Pat. No.10,940,012), the disclosures of which are incorporated herein byreference in its entireties.

BACKGROUND

An ankle joint may become severely damaged and painful due to arthritis,prior ankle surgery, bone fracture, osteoarthritis, and/or one or moreadditional conditions. Options for treating the injured ankle haveincluded anti-inflammatory and pain medications, braces, physicaltherapy, joint arthrodesis, and total ankle replacement.

Total ankle replacement generally comprises two components—one componentcoupled to the tibia and one component coupled to the talus. Thecomponents comprise articulation surfaces sized and configured to mimicthe range of motion of the ankle joint. For example, the talar portionmay comprise a component sized and configured to mimic the talar domeand the tibial portion may comprise an articulation surface configuredto mimic articulation of the tibia.

SUMMARY

In various embodiments, a talar implant is disclosed. The talar implantincludes a plate having an inferior surface configured for attachment toa talus. The plate has a post projecting from a superior surface of theplate and includes at least one threaded hole. A talar dome having aninferior surface is configured to face the plate and an opening in theinferior surface is shaped to receive the post. The talar dome includesat least one through hole having a threaded surface and a groove. Thegroove has a larger outer diameter than the threaded surface. At leastone fastener is configured to engage the threaded hole of the post andthe threaded surface of the through hole. The at least one fastener hasa groove that is aligned with the groove of the through hole when thefastener is inserted in the talar dome and the post. At least one clipis configured to engage the groove of the through hole of the talar domeand the groove of the fastener.

In various embodiments, an ankle prosthesis is disclosed. The ankleprosthesis includes a tibial component configured for attachment to atibia of a person, a plate having an inferior surface configured forattachment to a talus of the person, and a talar dome. The plateincludes a post projecting from a superior surface of the plate anddefines first and second threaded holes. The talar dome includes anarticulating surface configured to face the tibial component, aninferior surface configured to face the plate, and an opening in theinferior surface shaped to receive the post. The talar dome definesfirst and second through holes having respective first and secondthreaded surfaces with a diameter and first and second grooves,respectively. The first and second grooves have an outer diameter largerthan the diameter of the first and second threaded surfaces. First andsecond fasteners are configured to engage the first and second threadedholes, and the first and second threaded surfaces of the talar dome,respectively. The first and second fasteners each have a groove that isaligned with the first and second grooves of the talar dome,respectively, when the first and second fasteners are inserted in thetalar dome and the post. First and second clips are configured to engagethe first and second grooves of the first and second through holes andthe first and second grooves of the first and second fasteners,respectively.

In various embodiments, a method of inserting a talar implant isdisclosed. The method includes attaching a plate to a talus so that aninferior surface of the plate abuts the talus. The plate includes a postprojecting from a superior surface of the plate. The post includes atleast one threaded hole. The method further includes placing a talardome over the plate, so that an inferior surface of the talar dome abutsthe plate, and an opening in the inferior surface of the talar domereceives the post, the talar dome having at least one through hole. Thethrough hole includes a threaded surface and a groove. At least onefastener is inserted through the threaded surface of the through hole toengage the threaded hole of the post. The fastener includes a groove. Atleast one clip is inserted in the through hole, so as to engage thegroove of the through hole of the talar dome and the groove of thefastener.

BRIEF DESCRIPTION OF THE DRAWINGS

The features and advantages of the present invention will be more fullydisclosed in, or rendered obvious by the following detailed descriptionof the preferred embodiments, which are to be considered together withthe accompanying drawings wherein like numbers refer to like parts andfurther wherein:

FIG. 1 illustrates an anatomic view of an ankle joint.

FIG. 2 illustrates one embodiment of an ankle joint having a total anklereplacement system therein, in accordance with some embodiments.

FIG. 3 illustrates a top view of a talar implant including a talar domeand a talar plate, in accordance with some embodiments.

FIG. 4 illustrates a side perspective view of the talar implant of FIG.3 , in accordance with some embodiments.

FIG. 5 illustrates a side view of the talar implant of FIG. 3 , inaccordance with some embodiments.

FIG. 6 illustrates a cross-sectional view of the talar implant takenalong line 6-6 in FIG. 5 , in accordance with some embodiments.

FIG. 7 illustrates a top perspective view of a talar dome defining atleast one through hole, in accordance with some embodiments.

FIG. 8 illustrates a side view of the talar dome of FIG. 7 , inaccordance with some embodiments.

FIG. 9 illustrates a bottom view of the talar dome of FIG. 7 , inaccordance with some embodiments.

FIG. 10 illustrates a cross-sectional view of the talar dome taken alongline 7-7 in FIG. 9 , in accordance with some embodiments.

FIG. 11 illustrates a top view of a talar plate including a postconfigured to be coupled to a talar dome, in accordance with someembodiments.

FIG. 12 illustrates a side view of the plate of FIG. 11 , in accordancewith some embodiments.

FIG. 13 illustrates a fastener sized and configured to be inserted intoa through hole of a talar dome, in accordance with some embodiments.

FIG. 14 illustrates a clip configured to be coupled to a fastener, inaccordance with some embodiments.

FIG. 15 illustrates a cross-sectional view of the clip taken along line15-15 in FIG. 14 , in accordance with some embodiments.

FIG. 16 illustrates a C clip configured to be coupled to a fastener, inaccordance with some embodiments.

FIG. 17 illustrates a cross-sectional view of a talar implant includinga plate, talar dome, screw, and clip, in accordance with someembodiments.

FIG. 18 illustrates the talar implant of FIG. 17 with the screw insertedinto the talar dome and the post of the talar plate, in accordance withsome embodiments.

FIG. 19 illustrates a method of installing a talar implant, inaccordance with some embodiments.

DETAILED DESCRIPTION

The description of the exemplary embodiments is intended to be read inconnection with the accompanying drawings, which are to be consideredpart of the entire written description. In the description, relativeterms such as “lower,” “upper,” “horizontal,” “vertical,” “proximal,”“distal,” “above,” “below,” “up,” “down,” “top” and “bottom,” as well asderivatives thereof (e.g., “horizontally,” “downwardly,” “upwardly,”etc.) should be construed to refer to the orientation as then describedor as shown in the drawing under discussion. These relative terms arefor convenience of description and do not require that the apparatus beconstructed or operated in a particular orientation. Terms concerningattachments, coupling and the like, such as “connected” and“interconnected,” refer to a relationship wherein structures are securedor attached to one another either directly or indirectly throughintervening structures, as well as both movable or rigid attachments orrelationships, unless expressly described otherwise.

In various embodiments, a talar implant is disclosed. The talar implantincludes a plate having an inferior surface configured for attachment toa talus. The plate has a post projecting from a superior surface of theplate and includes at least one threaded hole. A talar dome having aninferior surface is configured to face the plate and an opening in theinferior surface is shaped to receive the post. The talar dome includesat least one through hole having a threaded surface and a groove. Thegroove has a larger outer diameter than the threaded surface. At leastone fastener is configured to engage the threaded hole of the post andthe threaded surface of the through hole. The at least one fastener hasa groove that is aligned with the groove of the through hole when thefastener is inserted in the talar dome and the post. At least one clipis configured to engage the groove of the through hole of the talar domeand the groove of the fastener.

FIG. 1 illustrates an anatomic view of an ankle joint 2. The ankle joint2 comprises a talus 4 in contact with a tibia 6 and a fibula 8. Acalcaneus 10 is located adjacent to the talus 4. In total anklereplacements, the talus 4 and the tibia 6 may be resected, or cut, toallow insertion of a talar implant and a tibial implant. FIG. 2illustrates the ankle joint 2 of FIG. 1 having a total ankle replacementsystem 12 inserted therein.

The total ankle replacement system 12 comprises a talar implant 14 and atibial implant 18. The talar implant 14 includes a talar dome having abody defining a talar articulation surface 16. The talar implant 14includes a plate coupled to the talus by one or more fasteners (notshown). The tibial implant 18 is sized and configured for installationinto the tibia 6. The tibial implant 18 comprises a body having anarticulation surface 20 and, in some embodiments, a tibial stem 24extending into the tibia 6 to anchor the tibial implant 18. The talarjoint surface 16 and the tibial joint surface 20 are mutually sized andconfigured to articulate. The joint surfaces 16, 20 replace the naturalankle joint surfaces, which are removed, to restore a range of motionthat mimics the natural joint. One or more holes may be formed in thetibia and/or the talus prior to and during insertion of the tibialimplant 18 or the talar implant 12. For example, in some embodiments, ahole is drilled starting in the bottom of the talus, extending throughthe talus and into the tibia. The hole may comprise, for example, a 6 mmhole configured to receive the stem 24 of the tibial implant 18.

The joint surfaces 16, 20 may be made of various materials, such as, forexample, polyethylene, high molecular weight polyethylene (HMWPE),rubber, titanium, titanium alloys, chrome cobalt, surgical steel, and/orany other suitable metal, ceramic, sintered glass, artificial bone,and/or any combination thereof. The joint surfaces 16, 20 may comprisedifferent materials. For example, the tibial joint surface 20 maycomprise a plastic or other non-metallic material and the talar jointsurface 16 may comprise a metal surface. Those skilled in the art willrecognize that any suitable combination of materials may be used.

FIGS. 3-6 illustrate a talar implant 100 including a talar dome 110 anda talar plate 120, in accordance with some embodiments. The talar plate120 includes a body 122 extending between an inferior surface 124 and asuperior surface 126 and defined by a perimeter wall 128. The inferiorsurface 124 is sized and configured to contact a resected talus. Forexample, the inferior surface 124 may comprise a planar surface, aconcave surface, and/or any desirably shaped surface configured to reston the surface of a resected (or partially-resected) talus. In theillustrated embodiment, the inferior surface 124 includes a planarsurface.

FIGS. 11-12 illustrate one embodiment of a talar plate 120 a, inaccordance with some embodiments. The body 122 defines a plurality offastener holes 125 extending through the body 122 from the superiorsurface 126 to the inferior surface 124. The fastener holes 125 aresized and configured to receive a fastener therethrough to couple thetalar plate 120 to a resected talus. In some embodiments, the fastenerholes 125 are configured to receive a fastener at a variable angle withrespect to a central axis of each of the fastener holes 125. In otherembodiments, one or more fastener holes 125 are omitted and/oralternative or additional attachment mechanisms may be included, such asfixed pegs, spikes, and/or any other suitable attachment mechanism.

With reference now to FIGS. 3-6 and 11-12 , in some embodiments, a post130 extends from the superior surface 126 of the talar plate 120. Thepost 130 extends a predetermined distance above the superior surface126. In the illustrated embodiment, the post 130 extends substantiallyperpendicular to the planar superior surface 126, although it will beappreciated that the post 130 can extend from the superior surface 126at any suitable angle, such as, for example, an angle substantiallybetween 45 and 90 degrees. The post 130 can include any suitable shape,such as, for example, a geometric (e.g., circular, cuboid, hexagonal,octagonal, etc.) or non-geometric shape. The post 130 may be formedintegrally with the talar plate 120 and/or may be coupled to the talarplate 120 using any suitable coupling mechanism, such as a screw, pin,or other fastener.

In some embodiments, the post 130 defines one or more fastener holes 132a, 132 b extending from an outer surface 134 of the post 130 at leastpartially into the post 130. Each of the one or more fastener holes 132a, 132 b is sized and configured to receive a distal portion of afastener, such as a screw, therein, as discussed in greater detailbelow. Each fastener hole 132 a, 132 b extends into the post 130 at afirst angle with respect to a plane defined by one or more surfaces ofthe talar plate 120, such as, for example, a plane defined by theinferior surface 124, the superior surface 126, a distal end of the post130, and/or any other suitable surface.

In some embodiments, the post 130 defines a central vertical axis 152and each of the holes 132 extend into the post 130 such that alongitudinal axis of the hole 132 does not extend through the centralvertical axis 152 of the post 130. For example, in some embodiments, alongitudinal axis of each of the holes 132 a, 132 b is offset oroff-center within the post 130. The combination of the first angle andthe offset may be referred to herein as a compound angle.

In some embodiments, each of the fastener holes 132 a, 132 b include aninternal threading 136 configured to couple the post 130 to a distalportion of a threaded screw, as discussed in greater detail below. Thefastener holes 132 a, 132 b may have similar and/or different internalthreading. In some embodiments, the internal threading 136 is omittedand a fastener is coupled to the post 130 using an additional and/oralternative coupling mechanism, such as a cross-pin, an adhesive, and/orany other suitable coupling mechanism.

FIGS. 7-10 illustrate one embodiment of a talar dome 110 a. Withreference now to FIGS. 3-10 , the talar dome 110, 110 a includes a body112 extending between a superior articulation surface 114 and aninferior plate contact surface 116. The body 112 has a predeterminedthickness between the articulation surface 114 and the plate contactsurface 116. The predetermined thickness can be constant and/orvariable. The articulation surface 114 is sized and configured tointerface with an opposing articulation surface of an opposing implantand/or bone structure. For example, in one embodiment, the articulationsurface 114 is sized and configured to interface with an articulationsurface of a tibial implant, such as, for example, the tibial implant 18shown in FIG. 2 . In another example, the articulation surface 114 issized and configured to interface with an articulation body locatedbetween a tibial implant 18 and the talar dome 110, 110 a, such as, forexample, a poly insert defining an articulation surface.

In some embodiments, the plate contact surface 116 comprises a surfaceconfigured to contact a superior surface 126 of the talar plate 120. Theplate contact surface 116 includes a surface complimentary to thesuperior surface 126 of the talar plate 120, such as, for example, aplanar surface, concave surface, convex surface, etc. For example, inthe illustrated embodiment, the plate contact surface 116 and thesuperior surface 126 each include generally planar surface. In variousembodiments, the plate contact surface 116 can include dimensions thatare greater than, less than, or equal to the dimensions of the superiorsurface 126 of the talar plate 120, such that the talar dome 110, 110 amay extend less than, up to, and/or beyond the peripheral edge 128 ofthe talar plate 120.

In some embodiments, the talar dome 110, 110 a defines a post hole 118extending from the plate contact surface 116 into the body 114 of thetalar dome 110, 110 a. The post hole 118 is sized and configured toreceive the post 130 of the talar plate 120 therein. The post hole 118has a complimentary cross-sectional shape with respect to the post 130.For example, in some embodiments, post 130 defines a substantiallygeometric shape, such as, for example, a circle, square, hexagon,octagon, etc., and the post hole 118 defines a complimentarysubstantially geometric cross-section. In some embodiments, the posthole 118 and the post 130 include complimentary shapes configured toallow insertion of the post 130 into the post hole 118 only when thetalar dome 110, 110 a and the talar plate 120 are arranged in one ormore predetermined alignments. For example, in some embodiments, thepost 130 may define a trapezoidal shape such that the post 130 fits intothe complimentary post hole 118 only when the short side of the post 130is aligned with a short side of the post hole 118. Although specificexamples are discussed herein, it will be appreciated that the post hole118 and/or the post 130 can have any suitable shape and are within thescope of this disclosure.

In some embodiments, the post hole 118 includes a depth sufficient toreceive the entire post 130 therein such that the plate contact surface116 of the talar dome 110, 110 a sits flush against the superior surface126 of the talar plate 120. The post 130 may have a diameter such that apartial friction fit exists between the post hole 118 and the post 130requires a force, such as a force applied by one or more fasteners toposition the talar dome 110, 110 a flush with the superior surface 126of the talar plate 120.

The talar dome 110, 110 a includes one or more through holes 140 a, 140b each extending along a respective longitudinal axis 146 a, 146 b fromthe articulation surface 114 through an interior wall 142 of the posthole 118. The through holes 140 a, 140 b are sized and configured toreceive a fastener therein (see FIG. 6 ). In some embodiments, eachthrough hole 140 a, 140 b includes an internal thread 144 extending overat least a portion of the through hole 140 a, 140 b. The internal thread144 is configured to couple a portion of a fastener, such as a screw, tothe talar dome 110. In some embodiments, the internal thread 144 issubstantially similar to the internal thread 136 of one or more holes132 formed in the post 130 such that a fastener having a single threadcan interact with each of the threads 136, 144 in each of a through hole140 a, 140 b in a talar dome 110 and a fastener hole 132 a, 132 b in apost 130.

In some embodiments, the longitudinal axis 146 a, 146 b of each of thethrough holes 140 a, 140 b extends through the talar dome 110, 110 a atan oblique angle with respect to the plate contact surface 116 of thetalar dome 110 and/or an oblique angle with respect to an axis extendingfrom an anterior edge 129 a of the body 112 to a posterior edge 129 b ofthe body 112. For example, and as shown in FIG. 9 , in some embodiments,each of the through holes 140 a, 140 b have an opening 148 a, 148 b inthe articulation surface 114 that is offset in a posterior directionwith respect to an opening 150 a, 150 b formed in the interior wall 142of the post hole 118. Similarly, and as shown in FIG. 10 , in someembodiments, the opening 148 a, 148 b of each through hole 140 a, 140 bformed in the articulation surface 114 is positioned in a superiordirection with respect to the holes 150 a, 150 b formed in the interiorwall 142 of the post hole 118. Although embodiments are discussed hereinwith specific positions of the openings 148 a, 148 b, 150 a, 150 b, itwill be appreciated that the superior/inferior, anterior/posterior,and/or medial/lateral position of each of the through holes 140 a, 140 bmay be adjusted.

In some embodiments, each of the through holes 140 a, 140 b includes afirst portion 152 a, 152 b having a first diameter and a second portion154 a, 154 b having a second diameter that is equal to or less than thefirst diameter. The first portion 152 a, 152 b of each of the respectivethrough holes 140 a, 140 b is sized and configured to receive a headportion of a fastener and the second portion 154 a, 154 b is sized andconfigured to receive a shaft or coupling portion of the fastenertherein (as discussed in greater detail with respect to FIGS. 17-18 ).

In some embodiments, each of the through holes 140 a, 140 b defines agroove 156 a, 156 b extending at least partially circumferentially aboutthe respective through hole 140 a, 140 b. Each of the grooves 156 a, 156b includes an outer diameter larger than the first diameter and/or thesecond diameter of the through holes 140 a, 140 b. In the illustratedembodiment, each of the grooves 156 a, 156 b are positionedcircumferentially about a first portion 152 a, 152 b of each of therespective through holes 140 a, 140 b and include an outer diametergreater than the first diameter of the through holes 140 a, 140 b,although it will be appreciated that the grooves 156 a-156 b can belocated circumferentially about the second portion 154 a, 154 b of eachthrough hole 140 a, 140 b and can have a diameter greater than thesecond portion 154 a, 154 b but less than the first portion 152 a, 152b. Each groove 156 a, 156 b is sized and configured to receive a cliptherein, as discussed in greater detail below.

The through holes 140 a, 140 b in the talar dome 110, 110 a areconfigured to align with the fastener holes 132 a, 132 b formed in thepost 130 when the post 130 is inserted into the post hole 118 and thetalar dome 110, 110 a is properly aligned with the talar plate 120. Forexample, in some embodiments, a central longitudinal axis of each of thethrough holes 140 a, 140 b is aligned with a central longitudinal axisof each of the fastener holes 132 a, 132 b in the post 130 when the post130 is inserted into the post hole 118. As discussed above, in someembodiments, the post hole 118 and/or the post 130 include a geometryconfigured to allow insertion of the post 130 into the post hole 118only in a predetermined alignment. The predetermined alignmentcorresponds to the through holes 140 a, 140 b and the post holes 132being aligned. In other embodiments, the talar dome 110, 110 a canrotate at least partially on the post 130 to allow the through holes 140a, 140 b to be brought into alignment with the fastener holes 132 a, 132b.

As illustrated in FIGS. 4-6 , in some embodiments, one or more fasteners160 a, 160 b are sized and configured to be inserted into the throughholes 140 a, 140 b and the fastener holes 132 a, 132 b. FIG. 13illustrates one embodiment of a fastener 160 c, in accordance with someembodiments. Each fastener 160 a-160 c is configured to engage thethreads 136 of a respective fastener hole 132 a, 132 b and/or thethreads 144 of a respective through hole 140 a, 140 b.

Each fastener 160 a-160 c includes a head 162 having a first diameterand a shaft 164 coupled to and extending from the head 162. The shaft164 extends substantially along a longitudinal axis from a first end 161a located adjacent to the head 162 to a second end 161 b and has asecond diameter. The first diameter of the head 162 may be greater than,less than, or equal to the second diameter of the shaft 164. The firstdiameter of the head 162 may be substantially equal to or slightlysmaller than the diameter of the first portion 152 a, 152 b of thethrough holes 140 a, 140 b and the second diameter may be substantiallyequal to or slightly smaller than diameter of the second portion 154 a,154 b of a through hole 140 a, 140 b. In some embodiments, the head 162defines a tool cavity 166 extending from the first end 161 a into thehead 162. The tool cavity 166 is sized and configured to receive adriving tool therein.

In some embodiments, each fastener 160 a-160 c includes a groove 168sized and configured to receive a clip therein. The groove 168 may beformed at least partially circumferentially about the head 162 of thefastener 160 a-160 c. Although embodiments are illustrated with a curved(or circular) circumferential groove 168, it will be appreciated thatthe circumferential groove 168 can include any suitable shape, such as,for example, circular, hexagonal, etc. In some embodiments, the groove168 is positioned on the head 162 such that the groove 168 is alignedwith the groove 154 a, 154 b of a respective through hole 140 a, 140 bwhen the fastener 160 a-160 c is fully inserted into a through hole 140a, 140 b and a fastener hole 132 a, 132 b.

As illustrated in FIGS. 4-6 , in some embodiments, a clip 180 a, 180 bis coupled to each of the fasteners 160 a, 160 b. FIGS. 14-15 illustrateone embodiment of a clip 180 c including a retaining ring, in accordancewith some embodiments. FIG. 16 illustrates one embodiment of a C clip180 d, in accordance with some embodiments. Each clip 180 a-180 d issized and configured to be received at least partially within a groove168 of a fastener 160 a-160 c and/or a groove 156 a, 156 b of a throughhole 140 a, 140 b.

In some embodiments, a clip 180 a-180 d is configured to be coupled to afastener 160 a-160 c prior to coupling the fastener 160 a-160 c to atalar implant 100. The clip 180 a-180 d is inserted into the groove 166formed in the head 162 of the fastener 160 a-160 c. In some embodiments,the clip 180 a-180 d includes at least one chamfer. For example, in someembodiments, a first side 182 of the clip can include a first chamferconfigured to interact with a circumferential inner wall of a throughhole 140 a, 140 b. In some embodiments, a clip 180 d can include a firstchamfer on a top surface and a second chamfer on a bottom surface. Asdiscussed in greater detail below, in some embodiments, the clip 180a-180 d is configured to prevent removal of a fastener 160 a-160 c froma talar dome 110, 110 a.

FIGS. 17-18 illustrate a process of coupling a talar dome 110 b to atalar plate 120 b using a first fastener 160 d, in accordance with someembodiments. FIG. 19 is a flowchart illustrating a method 200 ofinserting a talar implant 100 a, in accordance with some embodiments.The talar dome 110 b, talar plate 120 b, and fastener 160 d are similarto the talar domes 110, 110 a, talar plates 120, 120 a, and fasteners160 a-160 c previously described and similar description is not repeatedherein.

At step 202, the talar plate 120 b is attached to a talus. For example,in some embodiments, the talar plate 120 b can be coupled to a talushaving a resected surface formed specifically for insertion of the talarplate 120 b and/or during a prior ankle revision surgery. The talarplate 120 b is inserted such that the inferior surface 126 of the talarplate 120 b abuts the talus. At step 204, a talar dome 110 b is placedover the talar plate 120 b. The talar dome 110 b is positioned such thatthe inferior surface 116 of the talar dome 110 b abuts the superiorsurface 114 of the talar plate 120 b. The post hole 118 formed in theinferior surface 116 of the talar dome 110 b receives the post 130 ofthe talar plate 120 b. In some embodiments, the talar dome 110 b ispositioned over the talar plate 120 b without applying an impact force.

At step 206, a clip 180 e is coupled to a fastener 160 d. The clip 180 eis sized and configured to be received within a groove 166 defined aboutat least a portion of the circumference of the head 162 of the fastener160 d. In some embodiments, the clip 180 e can include a C clip and/or aretaining ring. At step 208, the fastener 160 d is inserted into thethrough hole 140 a to engage a threaded fastener hole 132 a formed inthe post 130 of the talar plate 120 b. The threads 170 of the fastener160 d couple to the threads 136 of the fastener hole 132 a. In someembodiments, the through hole 140 a includes threads 146 configured toengage a portion of the threads 170 of the fastener 160 d.

At step 210, the fastener 160 d is fully inserted into the through hole140 d such that the head 162 of the fastener 160 d is flush with and/orrecessed beneath the articulation surface 114 of the talar dome 110 b.When the fastener 160 d is inserted into the through hole 140 a, theclip 180 e is compressed into the groove 168 by a force applied by thethrough hole 140 a. In some embodiments, a chamfer formed on one or moresurfaces of the clip 180 e facilitate compression of the clip 180 e bythe wall of the through hole 140 a. The clip 180 e remains compressed inthe groove 166 until the fastener 160 d is fully inserted into thethrough hole 140 a. At step 212, when the groove 166 in the fastener 160d is aligned with the groove 156 in the through hole 140 a, the clip 180e expands from a compressed state to a partially compressed and/oruncompressed state. A portion of the clip 180 e is positioned in thegroove 156 and a portion of the clip 180 e remains in the groove 166 ofthe fastener 160 d. The clip 180 e applies an additional force tomaintain the fastener 160 d in a fixed position with respect to thetalar dome 110 b and the talar plate 120 b.

In some embodiments, and as discussed above, the through hole 140 aand/or the fastener hole 132 a can include longitudinal axes oriented atan oblique angle with respect to an inferior surface 116 of the talardome 110 b and/or can be offset from a central vertical axis of the post130 such that the longitudinal axes do not extend through the centralvertical axis of the post 130. In such embodiments, when the fastener160 d is inserted into the through hole 140 a and the fastener hole 132a, a longitudinal axis of the fastener 160 d is oriented at an obliqueangle with respect to the inferior surface 116 of the talar dome 110 band/or does not extend through the central vertical axis of the post130. Steps 206-210 may be repeated for one or more additional fasteners,although it will be appreciated that a single fastener 160 d may be usedin some embodiments.

Although the subject matter has been described in terms of exemplaryembodiments, it is not limited thereto. Rather, the appended claimsshould be construed broadly, to include other variants and embodiments,which may be made by those skilled in the art.

What is claimed is:
 1. A talar implant, comprising: a plate configuredfor attachment to a talus, the plate having a post projecting from asurface, the post having at least one threaded hole; a talar dome havinga surface configured to face the plate, and an opening in the surfaceshaped to receive the post, the talar dome defining at least one throughhole by a threaded surface and a groove, the groove having a largerouter diameter than the threaded surface; at least one fastenerconfigured to engage the threads that define the at least one throughhole of the post, the at least one fastener having a groove that isaligned with the when the fastener is inserted into the talar dome andthe post; and a clip configured to engage the groove of the through holeof the talar dome and the groove of the fastener.
 2. The talar implantof claim 1, wherein the at least one through hole has a longitudinalaxis that is oriented at an oblique angle with respect to the surfaceconfigured to face the plate.
 3. The talar implant of claim 2, whereinthe post has an axis, and the longitudinal axis of the at least onethrough hole does not extend through the post axis.
 4. The talar implantof claim 1, wherein the at least one fastener has a head, the headhaving a larger diameter than the threaded surface, and the groove ofthe fastener is located on a surface of the head.
 5. The talar implantof claim 1, wherein the clip is configured to prevent removal of thefastener from the talar dome while the clip engages the groove of thethrough hole and the groove of the fastener.
 6. A method of inserting atalar implant, comprising: attaching a plate to a talus so that theplate abuts the talus, the plate having a post projecting from asuperior surface of the plate, the post having at least one threadedhole; placing a talar dome over the plate, so that a surface of thetalar dome abuts the plate, and an opening in the surface of the talardome receives the post, the talar dome having at least one through hole,the through hole being defined by a threaded surface and a groove;inserting at least one fastener through the threaded surface thatdefines the through hole to engage the threaded hole of the post, thefastener having a groove; and inserting a clip into the through hole, soas to engage the groove of the through hole of the talar dome and thegroove of the fastener.
 7. The method of claim 6, wherein the step ofplacing the talar dome is performed without applying an impact to thetalar dome.
 8. The method implant of claim 6, wherein the step ofinserting at least one fastener is performed so that a longitudinal axisof the fastener is oriented at an oblique angle with respect to thesurface of the talar dome.
 9. The talar implant of claim 8, wherein thepost has a central axis, and the step of inserting at least one fasteneris performed so that the longitudinal axis of the at least one fastenerdoes not extend through the central axis.
 10. The method of claim 9,further comprising inserting a second fastener through a threadedsurface of a second through hole of the talar dome to engage a secondthreaded hole defined by the post, so that a longitudinal axis of thesecond fastener is oriented at an oblique angle with respect to thesurface of the talar dome, and the longitudinal axis of the secondfastener does not extend through the central axis.
 11. An ankleprosthesis comprising: a tibial component configured for attachment to atibia of a person; a plate configured for attachment to a talus of theperson, the plate having a post projecting from a surface and definingfirst and second threaded holes; a talar dome having an articulatingsurface configured to face the tibial component with a surfaceconfigured to face the plate, and an opening defined in the surfaceshaped to receive the post, the talar dome defining first and secondthrough holes by respective first and second threaded surfaces eachhaving a diameter and first and second grooves, respectively, the firstand second grooves having an outer diameter larger than the diameter ofthe first and second threaded surfaces; first and second fastenersconfigured to engage the first and second threaded holes, and the firstand second threaded surfaces of the talar dome, respectively, the firstand second fasteners each having a groove that is aligned with the firstand second grooves of the talar dome, respectively, when the first andsecond fasteners are inserted in the talar dome and the post; and firstand second clips configured to engage the first and second grooves ofthe first and second through holes and the first and second grooves ofthe first and second fasteners, respectively.
 12. The ankle prosthesisof claim 11, wherein each of the first and second through holes has arespective longitudinal axis that is oriented at an oblique angle withrespect to the surface of the talar dome.
 13. The ankle prosthesis ofclaim 12, wherein the post has a central axis, and the longitudinal axesof the first and second through holes do not extend through the centralvertical axis.
 14. The ankle prosthesis of claim 11, wherein the firstand second fasteners have first and second heads, respectively, thefirst and second heads having a larger diameter than the first andsecond threaded surfaces, and the first and second grooves of the firstand second fasteners are located on respective circumferential surfaceof the first and second heads.
 15. The ankle prosthesis of claim 11,wherein each of the first and second clips is a C clip having top andbottom chamfers on top and bottom surfaces thereof.